The present invention relates to a retaining wall block system. The system also includes a connector that is used to interlock blocks together and/or with soil reinforcement materials, such as a geogrid.
In recent years, segmental concrete retaining wall units which are dry stacked (i.e., built without the use of mortar) have become a widely accepted product for the construction of retaining walls. Examples of such products are described in U.S. Pat. No. Re. 34,314 (Forsberg ""314) and U.S. Pat. No. 5,294,216 (Sievert). Such products have gained popularity because they are mass produced, and thus relatively inexpensive. They are structurally sound, easy and relatively inexpensive to install, and couple the durability of concrete with the attractiveness of various architectural finishes.
The retaining wall system described in Forsberg ""314 has been particularly successful because of its use of a block design that includes, among other design elements, a unique pinning system that interlocks and aligns the retaining wall units, allowing structural strength and efficient rates of installation. This system has also shown considerable advantages in the construction of larger walls when combined with the use of geogrid tie-backs hooked over the pins, as described in U.S. Pat. No. 4,914,876 (Forsberg).
The construction of modular concrete retaining walls as described in Forsberg involves several steps. First, a leveling pad of dense base material or unreinforced concrete is placed, compacted and leveled. Second, the initial course of blocks is placed and leveled. Two pins are placed in each block into the pin holes. Third, core fill material, such as crushed rock, is placed in the cores of the blocks and spaces between the blocks to encourage drainage and add mass to the wall structure. Fourth, succeeding courses of the blocks are placed in a xe2x80x9crunning bondxe2x80x9d pattern such that each block is centered over the two blocks below it. This is done by placing the blocks so that the receiving cavities of the bottom of the block fit over the pins that have been placed in the units in the course below. As each course is placed, pins are placed in the blocks, the blocks are corefilled with drainage rock, and the area behind the course is backfilled and compacted until the wall reaches the desired height.
If wall height or loading conditions require it, the wall structure may be constructed using reinforced earth techniques such as geogrid reinforcement, geosynthetic reinforcement, or the use of inextensible materials such as steel mesh or mat. The use of geogrids are described in U.S. Pat. No. 4,914,876 (Forsberg). After placement of a course of blocks to the desired height, the geogrid material is placed so that the pins in the block penetrate the apertures of the geogrid. The geogrid is then laid back into the area behind the wall and put under tension by pulling back and staking the geogrid. Backfill is placed and compacted over the geogrid, and the construction sequence continues as described above until another layer of geogrid is called for in the planned design. The use of core fill in the blocks is known to enhance the wall system""s resistance to pull out of the geogrid from the wall blocks.
Though the pinning system described above can aid in producing a structurally sound wall, there is a desire to provide a block that is as lightweight as possible, relatively inexpensive and easy to produce. In addition it is desirable to have a block that connects well to geogrid reinforcement particularly in the upper section of a retaining wall where the normal load on the connection of the geogrid to the block is limited.
This invention is a retaining wall block and system that includes connectors used to align an upper course of blocks over a lower course. The block and connectors can be used with soil reinforcement materials.
In one aspect, this invention is a wall block connection system comprising a plurality of wall blocks, each wall block having a top surface, a bottom surface opposed to the top surface, first and second opposing side surfaces, a front face, and a rear face, the front and rear faces, top and bottom surfaces and side surfaces defining a block body, the block body including a head portion including the front face, a rear portion including the rear face, and first and second neck portions defining a core between the head and rear portions adjacent the rear portion, the head portion having at least one cavity defining a first web portion between the cavity and the first side surface and a second web portion between the cavity and the second side surface and a plurality of channel shaped connectors, each connector having first and second side segments connected by a bridge segment, the bridge segment having a pin element extending therefrom and being sized such that during construction of a wall, the first and second side segments straddle a web portion of the block. Each block may further comprise a partition dividing the cavity into first and second cavities. The cross-sectional shape of the pin element may be circular.
In another aspect, this invention is a retaining wall having at least a first lower course of blocks and a second upper course of blocks comprising the wall block and plurality of channel shaped connectors described above wherein the bridge segment is accommodated within the recessed region of the web portion so that the pin element extends upwardly into a cavity of a block in the upper course to thereby stabilize the relative positions of the blocks in the upper and lower courses.
In a third aspect, this invention is a method of making a retaining wall having at least a first lower course of wall blocks and a second upper course of wall blocks comprising the wall blocks and channel connectors described above, placing the wall blocks to form the first lower course of blocks, positioning the connectors on the blocks in the first course such that the first and second side segments of each connector straddle the first and second web portions and the bridge portion is accommodated within the recessed region of the first and second web portions and the pin element extends upwardly, and placing wall blocks over the first course of blocks to form the second course of wall blocks, the second course of blocks being positioned such that the cavity of each block in the second course of blocks receives an upwardly extending pin element.